1. Field of the Invention
The present invention relates to towbars which are interconnectable between a towing vehicle and a towed vehicle, in order to maintain proper spacing between the vehicles. For this purpose there is taught herein a universal curved towbar assembly which will mount to any conventional coupler ball hitch, on the rear of a towing vehicle, with the bumper of the towed vehicle being maintained through the provision of a redundant clamping arrangement. The present invention teaches a structure of a triangulated tubular steel design, with curved arm assemblies on the left and right side, together with a spreader bar assembly between the bumper mounting assemblies. Significantly, the draft force between the vehicles is shared only by the arms and spreader bar structure, while there is a separately tensionable portion of the safety chain engageable upon the towed vehicle.
2. Description of the Prior Art
Numerous towbar constructions are known in the prior art, and representative of prior approaches are the U.S. Pat. Nos., as follows:
______________________________________ FRANK 3,860,266 GAL 3,737,177 WOODKE 3,649,049 ORTIZ 3,610,447 HANSEN 3,492,022 HAYMAN 3,083,040 SAFFORD 3,072,419 HAWKINS 3,000,652 MILES 2,840,392 GENSINGER 2,830,829 ALBRECHT 2,830,827 KLEIN 2,790,521 GROSS 2,672,353 ROTH 2,518,641 KLEIN 2,488,415 ROGERS 2,481,685 JOHNSON 2,306,388 THORP 2,306,007 RODIN 2,212,480 ______________________________________
As will be more apparent hereinafter, the numerous towbar designs represented by these assembled patents do not begin to teach the specific advantages of the present disclosure. Specifically, none of these prior patents recognize advantages, which include, employing a pair of pivotable curved arms to allow the towing car's bumper to remain out of contact with the towbar assembly. Additionally, none of these exemplary prior patents include the redundant use of a frame safety chain, with a chain tensioning screw, so that the towed vehicle is securely held in a redundant fashion by the bumper clamps as well as the frame chain.
The patent to Frank represents a recent space-frame towbar assembly with the towing force being essentially applied to the frames of the respective vehicles. The spacing frame of Frank particularly avoids reliance on the bumpers, and requires careful adjustment of the chain assembly attached to the respective vehicle frames. As such, Frank does not recognize the use of a redundant frame chain in addition to a bumper clamping arrangement on the towed vehicle, nor does he teach any means for automatically ensuring that proper tensioning of the chains is assured.
The patent to Gal represents a vehicle towbar for small cars which also mounts directly to the frame of the towed vehicle, with the further points of attachment onto the bumper support bars. Therefore, Gal neither employs curved arm assemblies nor a redundant mounting arrangement as is taught by this disclosure.
The patent to Woodke similarly relies upon the bumper supports for tensioning a vehicle towbar, upward against the bumper, and is without any redundant mounting feature. While the arms of Woodke are adjustable, they are neither curved nor include the further feature of a spreader bar assembly for additional rigidity, as taught by this disclosure.
The patent to Ortiz similarly relies upon connecting a towed vehicle directly by mounting a chain assembly to the lower A-frame of the towed vehicle's front wheel assembly. The vehicle towbar of Hansen requires that the towed vehicle include two spaced part I members welded to the frame of the towed vehicle. As such, Hansen is not universal in application, and is further without recognition of the advantage of using curved arm assemblies.
The patent to Hayman employs conventional straight arm assemblies and does not suggest either the use of a spreader bar, or the use of a redundant attachment to the towed vehicle by a separately tensioning safety chain.
Safford, of common assignment with this invention, represents a single tensioning adjustment by using a frame chain together with flat pads for abutting the bumper of the vehicle to be towed. As such, Safford's early patent recognized neither a redundant mounting assembly, nor the advantages of the curved arm assemblies.
The patent to Hawkins illustrates a shock absorber, within a frame chain, to operate independently of the towbar. Hawkins' shock absorber is for the purpose of maintaining the rear end of the towing vehicle in contact with the ground. Significantly, Hawkins requires his tensioning chain to be attached to the towed vehicle at a point substantially below the points of attachment of the towbar assembly to the towed vehicle. As such, this triangulation effect is not equivalent to the redundant clamping assembly herein and, significantly, there is no recognition of the advantages of using curved arm assemblies within the towbar.
The patent to Miles illustrates a pivotable towbar wherein, the sole clamping engagement on the towed vehicle arises from the use of a tensioned chain to maintain a support against the vehicle bumper. Again, there is no increased safety factor from a redundant clamping assembly, nor any recognition of the advantages of using curved arms for the towbar structure.
The foldable towing mechanism taught by Gensinger is a permanent towbar to be mounted upon a service car, and is without any structural or functional similarity to the present universal curved towbar assembly.
The patent to Albrecht merely represents a telescoping tube being used as a towbar, and is also without recognition of the advantages realizable by the present universal towbar assembly.
The towbar of Klein illustrates yet another towbar construction of the prior art, without further pertinence to the present universal curved towbar assembly.
The patent to Gross, as well as the patents to Roth and the earlier patent to Klein, simply illustrates various known clamping assemblies for bumper mounted towbars. As such, they typify the prior art, and by contrast illustrate how the present universal curved towbar constitutes a significant improvement. The patent to Rogers represents a collapsible towbar which may be folded for storage. As such, it is categorically without functional or structural relationship to the present invention.
The early patent to Johnson illustrates an early towbar, which included a fulcrum so that the towed vehicle can be jacked up in an emergency.
The patent to Thorp represents a towbar in combination with a set of steering cables, attached to the steering knuckles of the towed vehicle. The steering cables provide a manner of turning the wheels of the towed vehicle, and do not constitute a redundant frame chain which can be tensioned upon the frame of the towed vehicle. Similarly, the patent to Rodin illustrates another form of automatic steering device as a part of a towbar.